Convergence in the bulb

How do millions of olfactory sensory neurons find their way from the nasal epithelium to the olfactory bulb? Here, all neurons expressing a single odorant receptor, the P2 receptor, are labeled with lacZ. Despite being dispersed in the epithelium, these neurons converge in the bulb upon a common set of targets.

We hypothesize that the target structure itself, the olfactory bulb, is important for this process, and that molecules are expressed in various hypothetical patterns to guide olfactory neurons.